Despite the many design advances made to vehicles, most on the road today do not provide drivers with a full 360° field of view (FOV). During the time a vehicle passing or being passed is not in view it may constitute a danger because the driver may be unaware of its presence or misjudge its distance.
While the windows of vehicles generally provide sufficient direct front and lateral views, most vehicles include side-view mirrors to provide additional rearward FOV. However, most side-view minors have a characteristic “blind-spot” between the area lateral to the side-view minor's field and behind the driver's direct lateral vision. As an adjacent vehicle approaches to pass in an adjacent lane, it is visible in the driver's rear-facing side-view mirror until it disappears from the viewing range of the minor. It remains out of sight until it appears again in the lateral vision of the driver. There is a similar blind spot on the passenger's side of the vehicle. One study has shown that, on average, drivers can see an angle of about 14.0° rearward in the driver's side-view minor and an angle of about 19.8° in the side mirror on the right. (Reed, M. P., Lehto, M. M., Flannagan, M. J. “Field of View in Passenger Car Minors,” University of Michigan Transportation Research Institute Report No. UMTRI-2000-23, Jun. 2000, Ann Arbor, Mich.).
In many vehicles the door frames and the body sections behind the back windows interfere with vision in the standard front windshield-mounted mirror. While side-view minors, mounted outside the vehicle's body, typically do not have this problem, efforts have been made to reduce or eliminate the above-described blind spots by modifying the side-view minors.
One solution has been to use spherically-convex side-view mirrors on the passenger side of the vehicle. Because a standard driver's side-view minor is a substantially planar reflective surface, so as to preserve a driver's perception of distance, a spherically convex mirror can be added as an attachment. However, spherically-convex mirrors provide a flawed view because an object reflected therein often appears significantly smaller. This is quite obvious when one looks at another vehicle in both the front windshield-mounted planar mirror and the passenger-side spherically-convex passenger-side mirror. The side-view mirror image is considerably smaller, which makes the vehicle appear to be more distant than it is actually. Thus, the increased FOV provided by the spherically-convex mirror is obtained at the cost of a reduction in image size, which, if not accounted for by a driver, can cause a dangerous misjudgment of distance.
There is a safety need for a vehicle mirror with an increased FOV that eliminates the lateral area blind spot behind a driver's lateral vision. Ideally, such a mirror would provide a FOV that extends from the side of the vehicle and outboard to a point where at least some part of an adjacent vehicle is visible until that vehicle can be seen in the driver's lateral vision. This can ensure that the viewed adjacent vehicle is, at least partially, in a driver's vision at all times. There is also a need for such mirrors to provide a reflected image that preserves the driver's ability to accurately judge the distance to other vehicles or objects by providing minimal vertical distortion of the image and as little horizontal distortion of the image as will still permit visualization of vehicles in the blind spot until they appear in the driver's lateral vision.